Is it possible to address a letter without adding street, just ZIP code and name? I want to send a friend a letter to a specific post office (he’s travelling around the US) for him to pick it up there. Does USPS accept such kind of letters or something? Thanks a lot!
It sounds like General Delivery is what you’re looking for.
I had a friend send me a postcard from overseas (Ireland, I think). It was simply addressed:
street
zip (five digit)
USA.
It got to me. It was to my home address, not General Delivery, though.
the city. state are unimportant if the zip is correct. The plus four on the zip will get it to the carrier route and building, making the number and street not as important any more.
The number and street are still necessary. A Zip+4 does not (necessarily) identify a single address. All three houses on my side of my street have the same one.
But presumably ZIP+4 will get the letter as far as the postman who does your round, who is likely to know where you live. So even if it doesn’t guarantee delivery, there must be a reasonable likelihood of successful delivery.
In many small towns where the postmaster already knows everyone, it could work.
I know that in at least one case the post office doesn’t even look at the City and State, just the zip. When I was stationed on Guam many of the places that I ordered online from said that they did not ship to Guam. We would order anyway, make sure that they shipped py USPS, and then put our address as Yigo, HI 96929. 96929 is the correct zip for Yigo, Guam. We received the packages just fine.
Or they may have looked at it, checked that there are no Yigos in Hawaii just to make sure, and sent it on. The city and state are intentionally redundant, so you don’t really need them. The city name, assuming the address is 100% correct, doesn’t give any information that the ZIP code alone doesn’t give.
“How little information can I put on mail to get it to a particular address?” is an interesting theoretical question (although not at all what the OP asked about), but redundancy in an address is a good thing.
When I was traveling I used to send postcards to a friend in rural NH by simply putting the ZIP code (or the ZIP, USA if overseas) and they all got to him. Nelson was such a character that the folks in the post office knew anything oddball was going to be for him.
Please read the OP carefully and note that post #2 answers the question accurately and completely. The OP does not want to mail a letter to someone’s house with only a Zip code.
I vaguely remember that the late lamented Spy Magazine did this as an experiment.
I think folks are aware of that, but the conversation has moved a little beyond the OP.
My mom grew up in a tiny rural town, and nobody used addresses. They’d just address letters to “Name, Town, State”
The OP might want to suggest to his friend that he leave instructions at the post office in the town he’s leaving to forward any General Delivery mail for him to General Delivery at his next destination.
I recall doing this when traveling with family many years ago. There’s no guarantee that you’ll still be in town when General Delivery mail intended for you arrives, so you want to make sure it follows you.
it’s known as the SD meander. it bifurcates, has large and small branches and dead ends.
It’s common along the Appalachian Trail, hikers will have gear/food/etc mailed to a PO along the trail to be held for them. They often include a note that if not picked up by a certain date to ship back to the sender, or to ship on to another PO along the trail. The postmasters in trailside towns see it a lot so they know the routine.
Postal worker checking in…
The machines use ALL the information. The first generation of OCR sorting machines would only read the bottom line CITY STATE ZIP/POST CODE (COUNTRY). The newer ones, called MULTI-LINE OCR, read the entire address. If there is conflicting information, it would, having checked the national database, weigh the various components, and go with the majority. If you address a letter to Chicago, California, but with the correct Illinois code, it will consider two hits for Chicago versus one hit for California, and will go to Chicago. If you address it To Chicago, California with a NY code, it’ll attempt to match the street name to find a majority. If this fails, it will go to a human operator.
Interestingly, postal codes are almost obsolete these days. They’re still useful for hand-written mail, but business mail can just use the DPID (Delivery Point Identification - sorry, unsure of what it’s called in the US) black barcode above the address, and that will identify an individual house or apartment, nationwide. Theoretically, the first human hands it will pass through are those of the local mailman on the beat, and of course, he won’t need the ZIP.
Intelligent Mail Barcode
William F. Buckley once noted that he received a piece of mail addressed simply to “the insufferable Mr. Buckley.” No address, no nothing. But it got to him.
Brilliant. 
You do get some strange ones. The theory is that - if it’s some sort of expensive express courier sort of article, you can take time to research a mangled address, but if it’s just a standard letter, then you just flick it off to the Dead Letter Office if you can’t work it out in a second or two. That’s the theory at least, but postal workers are human (yes, I know har har har) and if a standard letter looks unsually interesting or sentimental, we will go to a bit more trouble than we should. Bad address on a utility bill? DLO. Bad address on a card to a child in hospital from “Grandma” - we’ll put in some more effort.
One that sticks in my memory (and that I ended up hitting the telephone directories for) was to a Chinese restaurant in Sydney, obviously from a non English-speaking relative in mainland China who had copied what he thought was the address from a menu or business card. From memory, it went something like this:
Red Dragon Chinese Restaurant
Eat-in or take-away
BYO
No MSG
Let us cater for your next office function
Damn straight I made sure that one got there.